Cool butter: Cut the butter into small cubes, place them in one layer on a plate, and put them in the freezer for about 15 minutes; they should not be frozen but get really cold.
Mix flour, sugar, and salt in the food processor/stand mixer.
Add butter cubes and process shortly, about 10 pulses, but it depends on the machine you are using. The dough should resemble breadcrumbs.
Sprinkle with 2 tablespoons of icy water, and pulse a few times again until the dough comes together. Add the third tablespoon of water if necessary; sometimes I do add it, sometimes not; it depends on how exactly you weigh the flour and sometimes on the brand of the flour itself. The dough should hold together when you press a little bit of it between your fingers.
Refrigerate: Form a ball, divide it into two portions, press each piece into a disc and wrap the discs tightly in plastic foil. You will only need one portion to make about 15 pasties. Refrigerate for at least 2 hours or overnight.
Alternatively, you can use a ready-made sweet shortcrust pastry.